Aviation has been used for a large variety of purposes over the course of modern history, including warfare, reconnaissance, weather, and communications. The earliest aviation vehicle was the balloon, which is still widely used today for a variety of purposes. Balloons are filled with a highly buoyant gas (e.g., helium) that allows the balloon to ascend to a maximum altitude before inevitably descending based on a variety of factors, including weight of the payload and temperature of the gas. As a result, a balloon may have a limited mission life that can depend on descent of the balloon from a respective mission altitude.
One example of modern balloon use is for weather prediction and communications. Weather balloons can be used to transport scientific payloads into the upper atmosphere (e.g., stratosphere) as high as 130,000 feet. Once the balloon has reached the desired altitude, it may be desirable to have the balloon remain in a designated geographic area for as long as possible. Cross winds, however, tend to cause the balloon to drift in directions substantially parallel to the Earth's surface.